Viscose and method of manufacturing the same



Patented ()Ct. 28, 1930 UNITED STATES SAMUEL went, on NEW 7103K, 1v.

OF E V Y., AssIGNon-or' ONE-HALF TO NATHAN RAFIE, or- NEW YORK, N. Y.

vrsoosn Ann METHOD on AnUFAo'rURING THE SAME No Drawing. Application filed. March 1,

My invention relates to a new and improved, method of making viscose and a new and 1111- proved viscose resulting therefrom.

One of the objects of my invention is. to providea new and improved viscosewhich will be slowburning and which Wlll have considerable strength and tenacity.

Another object of my invention is to provide a new and improved method of produc- I mg a compound having the above mentioned characteristics. A preferred example ofthe above mentioned new and. improved compound and the new and improvedmethodof procuring the. same is herew th glv en, it being- .understood that this example is merely given by way of illustrationand that my 1nvention is not limited to the details, proportions or ingredients specified therein.

' said wood pulp is" treated by the zinc chloride solution which is preferably kept in a tank havingany well known means, for ma ntaining the requisite temperature of-about 5 C.

I first prefer to place the Wood pulp in the tank and then to add enough of the'zinc' chloride solution to fullycover the-said wood pulpin the tank. 7 1

The wood pulp is then allowed to steep 1n the zinc chloride solution at thistemperaturerfor'a period of about one hour anddur ing'this period I prefer not to agitate either the wood pulp or the solution. This treatmentis for the purpose of converting the cellulose into a hydrated cellulose, so that the cellulose has been rendered somewhat gelatinous, so that it can be formed into .blocksor sheets. a 1;: a

.I prefer not to agitate the cellulose and zinc chloride during this period of one; hour be 1924. Serial Kansas-s2.

cause such agitation would tend to cause the solution of thecellulose which is not desir able; as its conversion into a hydrated cellulose withoutsolution is desired. At the eX- piration of this one hour period the excess Zinc chlorideis drained off'by any suitable means. L V

A suffioient'quantity of 18% caustic soda solution, which has been chilled to a temperatu're of 5 (1, is now addedito the sheets of hydrated cellulose which are now in the 1 tank. The hydrated cellulose is treated with this caustic soda solution at the above men tioned temperature off5 C. for a period of about two hours also preferably without any agitation.

The treatment with the caustic soda 's olu tion converts the hydrated cellulose into an alkali cellulose.

I The: caustic soda solution is then drained from the contents of the tank. r l i 1 The sheets of treated cellulose are now sub jected to high pressure in a suitable hydraulic press so that they are formed intoa number of compressed blocks. The purpose of this compression is to force-out all excess solution and itisbelieved that no chemical action is The caused by means of the pressure alone. alkali c'ellulose is preferablymaintained at 5 C; during the compression so that the compressed blocks are also at the temperature of 5 C. The above temperature of 5 C. during the previously mentioned steps of the process is preferably secured by conducting all these operations in a room which is artificially cooled to a temperature of about 5 C.

The pressure in thehydraulic press is preferably maintained for about two hours so as to squeeze-out the proper'amount of excess solution.

'At the end of this still moist and they are then disintegrated by any convenient means so as to form a mass of separated 'fiberswhich tend to cling together and have a consistency similar to that of moist bread crumbs.

The commlnuted alkall cellulose is now placed. in jars made of an inert substance;

period theblocks are such as porcelain and kept in these jars;

which are suitably covered, for a period belbs. 01" dry cellulose tween seventy-two to ninety-six hours. During this period the alkali cellulose is kept the same temperature. The longer period 0t aging is preferably for treating alkal1 cellulose having a high copper number, that -s, cellulose having a high oxycellulose content. The jars in which the alkali cellulose is aged are kept covered so as to prevent the absorption of. carbon dioxide or other gases that may be present in the atmosphere.

The aired alkali cellulose, which is a cellulose hydrate, is then placed in any suitable revolving vessel and it is there treated w th carbon disulphide. I prefer to use carbon disulphide in the PL'OPOI'UO'HOT 20 lbs. to every batch originally containing 100 lbs. oi: dry cellulose. y p

The carbon disulphide slowly added during the period of treatment therewith and the barrel containing the batch is also revolved very slowly as otherwise the carbon disulphide would tend to explode, because of thelow boiling point of the carbon d1- sulphide, and because the reaction produces heat. v V I The treatment with the carbon disulphide is maintained for a period of about two hours and I prefer to add the carbon disulphide in 5 lb. batches during this period. I p'reter to add the additional quantities of carbon disulphideat fifteen minute intervals and by using a sufiiciently large barrel or tumbler the entire batch resulting from the original can be treated in a single barrel or tumbler r carbon disulphide before mentioned.

The above-mentioned step ofthis process is carried out at the above-mentioned temperature of 5 C. as before mentioned.

The excess carbon disulphide isthen removed as much as possible in any suitable manner from the cellulose compound formed by the action of the carbon disulphide as, for example, by allowing it toevaporate. However, since the temperature of thereaction mass must be kept quite low, namely, at a temperature of about 5, as later mentioned herein, this causes some of the carbon disulphide to remain unevaporated, sothat 1b IG- mains as a sulphur impurity in the solution formed when the caustic soda is added, as later mentioned herein. The alkali-cellulose hydrate which has been formed previous to the reaction with the carbon disulphide, reacts with the carbon disulphide to form sodium xanthogenate which is soluble in water.

The cellulose is then placed in a tank, preferably a cast-iron tank and enough 18% canstic soda solution is added at a temperature of 5 C. to completelydissolve the mass of cellulose compound by forming the before mentioned sodium salt. The amount of caustic soda solution which is added at this point varies according to the concentration of the with the 20 lbs. of

solution of the cellulose in the caustic soda which desired.

For example, if it is desired to make an artificial silk, it is preferable to have up to 5% ot the treated cellulose dissolve in the 18% caustic soda solution. In making a coarser thiead such as, for example, imitation horsehair the concentration of the solution the treated cellulose in the 18% caustic soda solution may beas high as 10%.

For making transparent sheets oi material the concentration of thedissolved cellulose in the 18% caustic soda solution may be 15% and even higher.

The contaminating agents in commercially manufactured products ot'fvarious types include certain sulphur salts.

However, the treatnientwith the 0; lion disulphide before mentioned of an alkali cellulose hydrate made from cellulose which has been previously hydrated by means of a zinc compound causes the formation 01 insolnble' zinc salts. These l'ast'mentioncd nie tallic'salts are insoluble in the solution of the sodium salt'finally fornied'as above mentioned, so that upon allowing the solution to stand forasuitable length of time these insoluble precipitates can be removed by any suitable liltering'me ans or by removing the supernatant liquor. I can only state the clieniical'reactions involved to the best of my knowledgeaiid I'do not wish to bind myself to an'y delinite chemical theory, because the cheinistry of cellulose is still obscure, but may state niy pi'esent opinion of the ji'eactions involved as follows? By'treatingthe bellulose' with Zinc chloride, a cellulose hydrate is formed whose consti tution is SUPPOSOd'tQ be (C,,H 1 O )(H O) lVhen this hydrate is treated with" tlie'sodium hydroxide solution, soluble sodium zincate. sodium chloride and a compound whose con stitution is'uiilrnownis formed. I believe that-this is'a compound in which the sodium hydroxide moleculehas been added to the cellulose aggregate and without resolving said aggregate. The treatment with carbon disulphide produces sodium xanthogeuate, whose exact formula is unknown. The sodium zincate reacts at this point to precipitate the impurities before mentioned. The subsequent treatment 'withsodium hydroxide solution produces the soluble sodium salt of this acidorwhat is known as a viscose solution, and thisisolution, being free from obiection able impurities, can be decomposed by various well khoWn solutions in "the well known manner to cause reversion to what in reality isdcellul'ds'e hydrate whichmay be dried and dehydra ed in thew ell known manner. This end product 'is' a viscose of a new and improved kind.

Thesolution thusmanufactured can now be utilized"industrially by any convenient and well knownmethods. 7

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The cellulose may be derived from any source in addition to the above mentioned, and my invention is not restricted to the use of zinc chloride as other solutions of metallic salts may be utilized in place of the zinc chloride and these will form insoluble metallic compounds whereby the objectionable impurities before mentioned may be either wholly or partially removed.

I believe that any hydrogen sulphide present as an impurity causes the formation and precipitation of zinc sulphide which is insoluble in the. neutral or alkaline'solution' formed by the addition of the caustic soda solution. Likewise, if any carbon disulphide has remained as an impurity, I believe that it forms either insoluble Zinc sulphocarbonate or else the carbon disulphide forms sodium sulphocarbonate, Which reacts with the soluble zinc salt to form insoluble and precipitated zinc sulphocarbonate.

present as an impurity also reacts with the soluble zinc salt to form insoluble zinc sulphocarbonate. Since the salts of other metals would produce similar reactions, I do not restrict my invention to the use of soluble zinc salt, although it is obvious that the production of a soluble Zinc salt by hydrating the raw cellulose with the zinc chloride is the preferred method, because a soluble zinc chloride has a direct action in the'process, and in addition the soluble zinc salt which is formed (namely, sodium zincate) is very uniformly distributed over the entire mass, so that it is not necessary to agitate the mass or the like. I

I prefer to have the entire process carried out at a temperature of 5 (3., by having all the implements, vessels, materials, etc. kept in a room which isartificially cooled to a temperature of 5 C. One of theimportant useful advantages of the new and improved cellulose solution above mentioned is that i when it is desired to make a coherent sheet of cellulose hydrate therefrom, it is merely necessary to evaporate a suiiicient amount of the solution in'heated molds until the solvent has evaporated. As'before noted, the effect of the preliminary treatment with Zinc chloride is to gelatinize or vulcanize the cellulose. Hence, a coherent sheet of gelatinized hydratedcellulose can be formed bymerely evaporating the solvent, and without the use of lnorganic salts or dllute aclds or the like, which have hitherto been neces sary to regenerate the cellulosein the form of coherent bodies.

Similarly in forming threads from the above mentioned solution, it is necessary to squirt the said solution through fine tubes into a coagulating medium, but it is not necessary to add desulphurizing substances to this coagulating medium.

lVhile the exact chemical nature of the 'lieved to be 'm-cellulosehydrate.

p I believe. that any sodium sulphocarbonate which is cellulose product described from the solution before mentioned, I has mot yet been deter-=' mined, 'I will refer :to it 1 as viscoid since this is the name generallyjgiven to the re-- generated cellulose; which has been formed from a cellulose Xanthate solutionby means This is be-' of inorganic salts or dilute acids.

I have described 'ai;preferred embodiment of: myJ-invention", but it isclear, that the numerous changes and ommissions could be:

made Witlioutfdeparting from its spirit, and in particular, I claim the novel articles of manufacture or compositions specified herein, independently of the processused for making them. I cannot determine whether the viscose or viscose solution produced as before specified is entirely free from the impurities before specified and hence I will define it as being partially free therefrom.

I claim:

1. In the art of manufacturing viscose, those steps which consist in forminga soluble cellulose Xanthogenate and substantially removing sulphur compounds therefrom before precipitating the viscose.

2. A method of making a viscose solution which consistsin hydrating cellulose in the presence of a zinc chloride solution and without dissolving the cellulose in the zinc chloride solution, causing the hydrated cellulose containing the said zinc chloride solution to then react with an alkali solution to form an alkali-cellulose-hydratecontaining a zinc zinc compound to form an insoluble zinc compound and removing the insoluble compound -l thus formed.

5. In the art of separating a dissolved zinc compound from a body of gelatinized cellulose which contains said compound, those steps which consist in causing the cellulose to react with carbon disulphide, and then forming an alkaline solution of the reaction massin which the zinc compounds are precipitated in soluble form.

6. Asa new and useful article of manufacture, a solution of an alkali metal cellulose Xanthogenate resulting directly from the interaction of a soluble cellulose compound and carbon disulphide, the solution of the reaction mass having been formed in an alkaline sollit) vent Without any purifying treatment forsremoving sulphur-=containing V impurities, said solution :being substantially-free from dissolvedsulphur-containing impurities.

7. As anew and useful articleof manufacture, a gelatinized viscoid free from'ither gelatinizing agent.

8. As a new-andusefulxavticleiof manufacture in reprecipita-ted agelatinized viscoid.

In testimony whereof Inhereunto *afiix'uny signature.

SAMUEL WEIN. 

